Closely spaced orthogonal dipole array

ABSTRACT

A broadband phased array antenna is shown wherein pairs of mutually orthogonal printed radiating elements, each one of such elements having a flared notch formed therein, are adapted to transmit or receive radio frequency energy having any one of a variety of polarizations.

United States Patent [191 Monser et al.

[ Sept. 17, 1974 CLOSELY SPACED ORTHOGONAL DIPOLE v ARRAY [75]Inventors: George J. Monser; George S.

Hardie; John R. Ehrhardt, Santa Barbara; Terry M. Smith, San Francisco,all of Calif.

[73] Assignee: Raytheon Company, Lexington,

Mass.

[22] Filed: Apr. 19, 1973 [21] Appl. No.: 352,760

[52] US. Cl 343/795, 343/797, 343/821 [51] Int. Cl. H0lq 9/28 [58] Fieldof Search 343/795, 797, 820, 821,

[56] References Cited UNITED STATES PATENTS 3,114,913 Alford 343/8217/1970 Perrotti et al 343/822 7/1973 Evans 343/821 Primary ExaminerEliLieberman Attorney, Agent, or Firm-Richard M. Sharkansky; Joseph D.Pannone; Philip J. McFarland [5 7] ABSTRACT A broadband phased arrayantenna is shown wherein pairs of mutually orthogonal printed radiatingelements, each one of such elements having a flared notch formedtherein, are adapted to transmit or receive radio frequency energyhaving any one of a variety of polarizations.

8 Claims, 1 Drawing Figure DESCRIPTION OF THE INVENTION This inventionrelates generally to phased array antennas and more particularly to suchantennas wherein the radiating elements thereof are comprised of aconducting metal deposited or printed on a substrate. The invention alsorelates to phased array antennas of such nature which are adapted totransmit or receive radio frequency energy having any one of a varietyof polarizations.

As is known in the art, it is frequently desirable to use a radiatingelement which may operate with one of a variety of polarizations (i.e.linear, circular, elliptical). One type of such a radiating element issometimes referred to as a double-ridged horn. A radiating element ofsuch type has a vertical feed and an independent horizontal feed, thephase centers associated with the feeds being coincident. In order toprovide efficient matching to free space over a wide frequency variationor bandwidth, say in the order of 2:1, it is generally required that thewidth of the horn be larger than M2 (where A is the nominal operatingfrequency of the antenna) and sometimes even up to the order of onewavelength (A).

A phased array antenna is generally comprised of a plurality ofradiating elements. To attain a relatively wide scan angle, say in theorder of 120, it is generally required that the phase centers ofadjacent ones of the plurality of radiating elements be displaced byless than All It follows, therefore, that while a double-ridged horn isadapted to operate with radio frequency energy ofone ofa variety ofpolarizations. such a radiating element may not readily be used in aphased array antenna having a relatively wide bandwidth and relativelylarge scan angle.

As is also known in the art, radio frequency antennas are sometimescomprised of a radiating element formed from a conducting metal printedor deposited on a substrate. Such antennas have the advantage of lighterweight compared to waveguide antennas as a double-ridged horn. However.known antennas having printed radiating elements are not generallyadapted to transmit or receive radio frequency energy having any one ofa variety of polarizations.

SUMMARY OF THE INVENTION With this background of the invention in mind,it is an object of this invention to provide an improved phased arrayantenna.

It is another object of the invention to provide an improved phasedarray antenna adapted to operate in one of a number of polarizations. I

These and other objects of the invention are attained generally byproviding a pair of mutually orthogonal printed radiating elements, eachone of such elements having a flared notch formed therein.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing features of thisinvention, as well as the invention itself, may be more fully understoodfrom the following detailed description read together with theaccompanying drawing, the single FIGURE of which shows an exploded,perspective view of a phased array antenna according to the invention.

DESCRIPTION OF THE PREFERRED v EMBODIMENT Referring now to the FIGURE, aphased array antenna 10 is shown to include a plurality, here five, ofvertical radiating elements 12 12, arranged in a linear array, apluraity, here five, of horizontal radiating elements 14 I4 arranged ina linear array, and a back-wall 15. Back wall 15 is comprised of asingle planar substrate of dielectirc material having a conductingmaterial, here copper, deposited or printed by any conventional methodto make the face portion 17 thereof a conventional ground plane for theradiating elements.

Each one of the vertical radiating elements l2 12 (as shown most clearlyin the exploded view of radiating element 12 is identical inconstruction and includes a planar substrate 16 16 of dielectricmaterial, a formed layer of conducting material, here copper, depositedor printed by any convenient method on a portion of one side of theplanar substrate 16 16 and a feed line 18 18 The conducting materialdeposited on back wall I5 and the conducting material deposited on aportion of each one of the vertical radiating elements l2 12 areconnected by a conventional solder joint (not numbered).

Considering in detail an exemplary one of the vertical radiatingelements, say vertical radiating element 12 it may be seen that theformed layer of conducting material is symmetrically printed aboutcenter line 20 to produce an upper portion 22 of the conducting materialseparated from a lower portion 24 of the conducting material by a notch26. The notch 26 is flared from a narrow portion to a wide portion, herein one step. The narrow portion has a width a and the wide portion has awidth b. A slot, not numbered, is formed within the substrate 26 along aportion of the center line 20, as shown, to permit alignment of thevertical radiating element 12,, with the horizontal radiating element 14The feed line 18 here coaxial cable, is passed through back plate 15.One portion of such cable is orthogonal to the plane of back plate 15and a second portion of such cable is parallel to such back plate. Theformer portion of the cable is displaced from the plane of thehorizontal radiating elements by a dimension 0 and the second portion ofsuch cable is displaced from the plane of back wall 15 by a dimension d.

Considering in detail an exemplary one of the feed lines 18 18,, say 18such feed line is here a coaxial cable having its outer conductorconnected by a conventional solderjoint (not numbered) to the upperportion 22 of the conducting material and its inner conductor connected,again as by a conventional solder joint (not numbered) to the lowerportion 24 of the conducting material. The dielectric sleeve, notnumbered, of the coaxial cable 18 insulates the inner con ductor of thecoaxial cable as such conductor passes across the narrow portion ofnotch 26.

Referring now to the horizontal radiating elements I4 14 it is firstnoted that the individual ones of such elements are similar inconstruction to the vertical radiating elements; here, however, thehorizontal radiating elements 14 14 are formed on a single planarsubstrate 30 of dielectric material. Each one of such horizontalradiating elements 14, 14,, is made up of:

a formed layer of conducting material, here copper, deposited or printedon a portion of one side of the planar substrate 30; and a feed line32,- 32 The conducting material deposited on back wall 15 and theconducting material deposited on a portion of each one of the horizontalradiating elements are connected by a conventional solder joint (notnumbered). When assembled, the phased array antenna is a rigid unitarystructure, the back wall serving as an integral part of such antenna asa conventional ground plane for both the horizontal radiating elementsand the vertical radiating elements.

Adjacent ones of the horizontal radiating elements, although physicallyjoined together, may be considered to be separate identical units,divided from each other along dotted lines 34 34 An exemplary one ofsuch units, say 14 is shown in detail to have the layer of conductingmaterial deposited thereon symmetrically about center line on a portionof substrate 30. Aleft hand portion 36 of the conducting material isseparated from a right hand portion 38 of the conducting material by anotch 40. The notch 40 is flared from a narrow portion to a wide portionhere in one step. The narrow portion has'a width e and the wide portionhas a width Feed lines 32, 32 are here coaxial cables. Considering indetail an exemplary one thereof, say 32 the outer conductor is solderedto the left hand portion 36 'of the conducting material and the innerconductor of such cable is soldered to the right hand portion 38 of theconducting material. A sleeve, not numbered, of insulating materialsurrounds the inner conductor of such cable as such conductor passesacross the narrow portion of the notch 40. Considering exemplary feedline 32 such feed line has one portion thereof orthogonal to the planeof back wall 15 and a second portion parallel to the back wall. Theformer portion of the cable is displaced from the plane of the verticalradiating element disposed along its center line, here verticalradiating element 12,, by a dimension g and the second portion of suchcable is displaced from the backwall 15 by a dimension [2.

When the phased array antenna 10 is operating in either the transmitmode or the receive mode, radio frequency energy passes between freespace and the wide portion of notches 26, 40 and such energy also passesbetween the narrow portion and the wide portion of such notches. Theradio frequency energy passing through the narrow portion of such notchin the vicinity where the inner conductor of feed lines 32 32 and l8 18passes across such narrow portion is associated with a potentialdifference developed between the inner conductor and the outer conductorof such feed lines. It is noted that when feed lines l8 18 are connectedto a suitable bus, here represented by dotted line 28, the verticalradiating elements 12, 12;, act as a vertically polarized antenna andlikewise, when feed lines 32 32 are connected to a suitable bus, hererepresented by dotted line 42, the horizontal radiating elements act asa horizontally polarized antenna. The relative phase shift of the radiofrequency energy, between adjacent feed lines, defines the scan angle ofthe antenna in a conventional manner. Such phase shift may be providedby convential phase shifters (not shown). It is further noted that byhaving the center conductors of the coaxial cables passing across thenarrow portion of each one of the notches substantially coincidentelectrically, the phase center associated with each one of thehorizontal radiating elements 14 14 and each one of the verticalradiating elements 12, 12 will be substantially disposed along a line inthe plane of the substrate 30 and parallel to the plane of back wall 15.Such line is indicated by dotted line 46. It follows then that byproperly adjusting the relative amplitude and phase between the radiofrequency energy on the bus represented by dotted line 42 and the radiofrequency energy on the bus represented by the dotted line 28, thephasedarray antenna 10 may transmit or receive radio frequency energy havingany one of a variety of polarizations.

The phased array antenna 10 has been built and found effective to matchradio frequency energy to free space over'a 2:1 bandwidth and over ascan angle. The parameters used were:

Dimension a 0.] inches Dimension b 0.5 inches Dimension c 0.625 inchesDimension d 0.65 inches Dimension e 0.] inches Dimension f= 0.5 inchesDimension g 0.425 inches Dimension 11 0.475 inches Height of VerticalRadiating Element 2.40 inches coaxial cable. Also, the notch may beflared from a narrow portion to a wide portion in other than one step,for example it may flare in more thanone step or it may flare accordingto a continuous function such as in linear function or in a parabolicfunction.

It is felt, therefore, that this invention should not be restricted toits disclosed embodiment but rather should be limited only by the spiritand scope of the appended claims.

What is claimed is:

I. An antenna element comprising: a pair of planar radiating elements,one thereof disposed in a plane orthogonal to the other one thereof, thephase center of one of such planar radiating elements being separatedfrom the phase center of the other one of such planar radiating elementsby less than )t/4 (where )t is the operating wavelength of the antennaelement), each one of such radiating elements including:

a. a radio frequency feed line; and,

b. a planar sheet of conducting material having a flared notch formedtherein, the feed line being coupled across such flared notch.

2. The antenna element recited in claim 1 wherein each one of suchradiating elements includes:

a planar substrate; and-wherein the conducting material is deposited ona portion of such substrate, the flared notch formed therein having anarrow portion and a wide portion, the feed line being coupled acrossthe narrow portion of such notch.

3. An antenna comprising: a linear array of antenna elements, each onethereof including: a pair of planar radiating elements, one of such pairof elements disposed in a plane orthogonal to the other one of such pairof elements, such pair of elements having phase centers coincident toless than M4 (where A is the operating wavelength of the antenna), eachone of such radiating elements including:

a. a radio frequency feed line; and,

a planar sheet of conducting material having a flared notch formedtherein, the feed line being conv nected across such flared notch.

4. The antenna recited in claim 3 wherein each one of the pair of planarradiating elements has one planar radiating element disposed in a commonplane.

5. The antenna recited in claim 4 including addition ally a ground planeelement common to the antenna elements and disposed orthogonal to eachone of the pair of planar radiating elements.

6. The antenna recited in claim 3 wherein each one of such planarradiating elements includes a planar substrate; and, wherein theconducting material is deposited on a portion of such substrate, theflared notch formed therein having a narrow portion and a wide portion,the feed line being coupled across the narrow portion of such notch.

7. The antenna recited in claim 6 wherein each one of the pair of planarradiating elements has one of the pair of substrates disposed in acommon plane.

8. The antenna recited in claim 7 including additionally a ground planeelement common to the antenna elements and disposed orthogonally to eachone of the pair of substrates of the radiating elements.

1. An antenna element comprising: a pair of planar radiating elements,one thereof disposed in a plane orthogonal to the other one thereof, thephase center of one of such planar radiating elements being separatedfrom the phase center of the other one of such planar radiating elementsby less than lambda /4 (where lambda is the operating wavelength of theantenna element), each one of such radiating elements including: a. aradio frequency feed line; and, b. a planar sheet of conducting materialhaving a flared notch formed therein, the feed line being coupled acrosssuch flared notch.
 2. The antenna element recited in claim 1 whereineach one of such radiating elements includes: a planar substrate; andwherein the conducting material is deposited on a portion of suchsubstrate, the flared notch formed therein having a narrow portion and awide portion, the feed line being coupled across the narrow portion ofsuch notch.
 3. An antenna comprising: a linear array of antennaelements, each one thereof including: a pair of planar radiatingelements, one of such pair of elements disposed in a plane orthogonal tothe other one of such pair of elements, such pair of elements havingphase centers coincident to less than lambda /4 (where lambda is theoperating wavelength of the antenna), each one of such radiatingelements including: a. a radio frequency feed line; and, a planar sheetof conducting material having a flared notch formed therein, the feedline being connected across such flared notch.
 4. The antenna recited inclaim 3 wherein each one of the pair of planar radiating elements hasone planar radiating element disposed in a common plane.
 5. The antennarecited in claim 4 including additionally a ground plane element commonto the antenna elements and disposed orthogonal to each one of the pairof planar radiating elements.
 6. The antenna recited in claim 3 whereineach one of such planar radiating elements includes a planar substrate;and, wherein the conducting material is deposited on a portion of suchsubstrate, the flared notch formed therein having a Narrow portion and awide portion, the feed line being coupled across the narrow portion ofsuch notch.
 7. The antenna recited in claim 6 wherein each one of thepair of planar radiating elements has one of the pair of substratesdisposed in a common plane.
 8. The antenna recited in claim 7 includingadditionally a ground plane element common to the antenna elements anddisposed orthogonally to each one of the pair of substrates of theradiating elements.